The purpose of the proposed project is to examine in detail the possibility that subtle midfrequency hearing dysfunction that goes undetected by pure-tone audiometry may exist in noise-exposed listeners. There is sufficient evidence to support this possibility available from: (1) correlations between cochlear histology and pure-tone thresholds; (2) studies of TTS in man; and (3) preliminary studies of subtle midfrequency dysfunction in noise-exposed persons. In addition, recent data imply that the presence of undetected midfrequency pathology may explain some of the difficulty that noise-exposed listeners have in understanding speech, especially in noisy environments. The present project plans to evaluate midfrequency auditory function in a large sample of noise-exposed listeners and examine the relationship between the extent of dysfunction and communicative breakdown. Measures used to assess midfrequency dysfunction include: (1) psychophysical tuning curves; (2) pure-tone masking patterns; (3) two-tone unmasking; and (4) masked speech reception threshold. In addition, two measures will be used to assess communication breakdown. These are the California Consonant Test and the Hearing Performance Inventory.